1. Field of the Invention
The present invention relates to a saddle type vehicle. More particularly to a saddle type vehicle including a main frame of a monocoque structure wherein an air cleaner is built in the main frame.
2. Description of Background Art
A conventional saddle type vehicle is known wherein a main frame of a so-called monocoque structure includes an air cleaner built in the inside thereof which is formed in a hollow state. An engine is placed on the lower side of the main frame. In the main frame of the monocoque structure, air passes through the inside of the main frame, is purified by the air cleaner and is supplied to the engine through an intake passage connected to the main frame. See, for example, Japanese Utility Model Publication No. Hei 7-42946.
In Japanese Utility Model Publication No. Hei 7-42946, a structure which uses a member formed as a separate member from a main frame is used in order to seal an air system such as an intake duct. However, in a main frame of a monocoque structure, securing of the sealing property is a problem in comparison with an alternative case in which an air cleaner case is configured from a part of a resin to obtain an optimum structure for an engine configuration or a vehicle configuration. In particular, in the case of an air clear of a monocoque structure which uses a main frame, a sealing connection between an engine which vibrates and the air cleaner for which a vehicle body frame itself is used is difficult. Especially, in a multi-cylinder engine, where a difference in tolerance exists between individual cylinder units, it is a very difficult problem to maintain the sealability.